A hollow insulating sphere with an inner radius of 780 cm

Question

Solve the all parts of given question:

Question: A hollow insulating sphere with an inner radius of 7.80 cm and outer radius of 13.5 cm has a uniform charge density of 91.1 μC/m³ distributed throughout the volume between .

Part A: If we are going to use Gauss' Law to find the electric field at r = 10.83 cm, we need to know the "charge enclosed" by a surface. What "charge enclosed" should we use?

Part B: If we want to use Gauss' Law to find the electric field at r = 19.0 cm, what "charge enclosed" should we use?

I need expert help to solve the above question.